[2] Risk factors include diabetes, high blood pressure, multiple gestation (being pregnant with more than one baby), being either obese or underweight, vaginal infections, air pollution exposure, tobacco smoking, and psychological stress.

[12] Four different pathways have been identified that can result in preterm birth and have considerable evidence: precocious fetal endocrine activation, uterine overdistension (placental abruption), decidual bleeding, and intrauterine inflammation or infection.

[43] Studies on type of work and physical activity have given conflicting results, but it is opined that stressful conditions, hard labor, and long hours are probably linked to preterm birth.

[49][needs update] A study conducted in Malaysia in 2015 showed a similar trend, with marital status being significantly associated with preterm birth.

[51] Medications during pregnancy, living conditions, air pollution, smoking, illicit drugs or alcohol, infection, or physical trauma may also cause a preterm birth.

The Nigerian cultural method of abdominal massage has been shown to result in 19% preterm birth among women in Nigeria, plus many other adverse outcomes for the mother and baby.

[70] It has been reported that asymptomatic colonization of the decidua occurs in up to 70% of women at term using a DNA probe suggesting that the presence of micro-organism alone may be insufficient to initiate the infectious response.

[30] This same study found statistically significant relative risks of maternal anemia, intrapartum fever, unknown bleeding, renal disease, placental previa, hydramnios, placenta abruption, and pregnancy-induced hypertension with the absence of prenatal care.

[90] Technologies under research and development to facilitate earlier diagnosis of preterm births include sanitary pads that identify biomarkers such as fFN and PAMG-1 and others, when placed into the vagina.

[95] Many countries have established specific programs to protect pregnant women from hazardous or night-shift work and to provide them with time for prenatal visits and paid pregnancy-leave.

[95] Progestogens—often given in the form of vaginal[116] progesterone or hydroxyprogesterone caproate—relax the uterine musculature, maintain cervical length, and possess anti-inflammatory properties; all of which invoke physiological and anatomical changes considered to be beneficial in reducing preterm birth.

Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth.

To try to reduce the risk of this outcome, pregnant mothers with threatened premature delivery prior to 34 weeks are often administered at least one course of glucocorticoids, an antenatal steroid that crosses the placental barrier and stimulates the production of surfactant in the lungs of the baby.

A 2015 Cochrane review (updated in 2022) supports the use of repeat dose(s) of prenatal corticosteroids for women still at risk of preterm birth seven days or more after an initial course.

[127] A Cochrane review from 2020 recommends the use of a single course of antenatal corticosteroids to accelerate fetal lung maturation in women at risk of preterm birth.

[133] A number of medications may be useful to delay delivery including: nonsteroidal anti-inflammatory drugs, calcium channel blockers, beta mimetics, and atosiban.

[135] This delay, however, may be sufficient to allow the pregnant woman to be transferred to a center specialized for management of preterm deliveries and give administered corticosteroids to reduce neonatal organ immaturity.

In the NICU, premature babies are kept under radiant warmers or in incubators (also called isolettes), which are bassinets enclosed in plastic with climate control equipment designed to keep them warm and limit their exposure to germs.

[144] For extremely preterm babies (born before 28 weeks' gestation), targeting a higher versus a lower oxygen saturation range makes little or no difference overall to the risk of death or major disability.

[149] The American Academy of Pediatrics recommended feeding preterm infants human milk, finding "significant short- and long-term beneficial effects," including lower rates of necrotizing enterocolitis (NEC).

Fortification of breast milk or formula by adding extra nutrients is an approach often taken for feeding preterm infants, with the goal of meeting the high nutritional demand.

[149] In addition, the ideal timing of enteral feeds to prevent side effects such as necrotising enterocolitis or mortality in preterm infants who require a packed red blood cell transfusion is not clear.

[148] The risks or adverse effects associated with high-volume enteral feeding of preterm infants including aspiration pneumonia, reflux, apnea, and sudden oxygen desaturation episodes have not been reported in the trials considered in a 2021 systematic review.

[173] If the infant is on aminoglycosides such as gentamicin for less than five days they should be monitored and have a follow-up 6–7 months of being discharged from the hospital to ensure there is no late onset hearing loss due to the medication.

[213] The record for the smallest premature baby to survive was held for a considerable amount of time by Madeline Mann, who was born in 1989 at 26 weeks, weighing 280.0 g (9.875 oz) and measuring 24 cm (9.5 in) long.

The larger twin left the hospital at the end of December, while the smaller remained there until 10 February 2005 by which time her weight had increased to 1.18 kg (2 lb 10 oz).

[218] Generally healthy, the twins had to undergo laser eye surgery to correct vision problems, a common occurrence among premature babies.

In May 2019, Sharp Mary Birch Hospital for Women & Newborns in San Diego announced that a baby nicknamed "Saybie" had been discharged almost five months after being born at 23 weeks' gestation and weighing 244 g (8.6 oz).

[229][231][232][233][234][235][236] Behaviourally, adolescents who were born very preterm and/or very low birth weight have similar self-reports of quality of life, health status and self-esteem as term controls.

[228] Nosarti and colleagues previously hypothesised that maturational patterns in preterm brains were consistent with the age-related stages typically observed in younger subjects.